1. Field of the Invention
This invention relates to a suspended conveyor line of a poultry processing plant, wherein birds are suspended by their legs on shackles or poultry hanger assemblies, and the shackles carry the bird along a processing path where the birds are, for example, cut apart. More particularly, the invention relates to a rotary bird hanger assembly which can be rotated so as to present the bird in different positions to the cut up equipment, etc.
2. Description of Related Art
In modern poultry processing plants, chickens, turkeys and other birds raised for commercial slaughter are moved through a poultry processing line where they are sequentially defeathered, eviscerated, cut up, and packaged for shipment to wholesale and retail consumers. In such a plant, it is common for the poultry carcasses to be suspended by their legs from a suspended shackle conveyor. The conveyor typically includes a suspended conveyor rail and a series of bird support shackles, each of which includes a trolley for rolling along the conveyor rail and a bird hanger suspended below the trolley, with a drive chain connecting the shackles in equally spaced series. The bird hangers have a pair of spaced depending stirrups that are configured to receive and releasably hold the hocks of the birds.
With this arrangement, the workers can suspend birds by their legs or hocks from the shackles by slipping their hocks into the stirrups. The spaced suspension of the birds along the conveyor system allows the birds to be moved sequentially through the various processing stations, such as cut up machines, for serial processing of large numbers of the carcasses.
As poultry carcasses are processed at the various processing stations of the poultry line, the carcasses are turned to present the carcasses in various attitudes to the different processing machinery to accommodate each of the processing steps. In some of these stations, it is desirable to present the carcass breast first, and other stations back first, and still other stations side first. In order to turn the bird, poultry shackles have been developed which include a lower bird hanger that is rotatably mounted to the trolley assembly, and a turning gear mounted to the bird hanger. The turning gear typically has slots formed therein that engage turning pins spaced at predetermined intervals along the poultry processing path, so that when a slot of a turning gear reaches the turning pin, the turning gear "walks around" the turning pin, so as to rotate the bird hanger approximately 90.degree..
In order to keep the bird hanger from inadvertently rotating with respect to the trolley assembly, the turning gear typically includes flat surfaces about its periphery, and these flat surfaces are arranged to move adjacent guide rails extending parallel to and straddling the turning gear, so that no inadvertent turning of the bird hanger occurs. An example of this type of rotary shackle is disclosed in U.S. Pat. No. 5,487,700.
While the above described rotary shackles have met with success in the poultry processing industry, there are times when a poultry conveyor system must be able to move the poultry shackles up and down inclines, around curves, and about combinations of curves and inclines. While the prior art turning gears and guide rails are effective to retain the bird hanger of a poultry shackle in an approximately fixed attitude along rectilinear runs of a conveyor system, the turning gears and their necessary guide rails are more difficult to construct and operate for movement of the shackles about curves and into inclines of the processing path, and the guide rails typically are interrupted at the positions along the path where the shackles negotiate a turn, etc. Therefore, it has been customary to move poultry shackles at certain intervals through a processing line without using the guide rails to maintain the poultry shackles in a fixed attitude.
U.S. Pat. No. 5,092,815 illustrates a rotary shackle assembly which has a spring loaded ball bearing that registers with a detent which tends to hold the shackle in a non-rotary position with respect to its trolley; however, the ball and detent arrangement provides only a light restraining force to the tendency of the shackle to rotate with respect to its trolley, and the absence of a firm lock does not solve the problem of inadvertent rotation of the poultry carcass with respect to its trolley during those spans of the trolley system where the shackle is being elevated or turned. Also, this type of system still requires the guide rails at the processing stations.
Thus, it can be understood that it would be desirable to have a releasable lock system for a rotary shackle of a poultry processing line, whereby the shackle can be freely rotated with respect to its trolley at predetermined positions along the processing line, and can be firmly held against rotation at all other positions along the processing line without the use of external guide rails.